Friday, June 27, 2008

Colour - naming dyes, pigments and paints

While I continue to construct a table of all the different pigment names and colour names (which is turning into a mammoth project - although the end is in sight!) I thought I'd better get on with my planned post about how colours and pigments are named.

My first awareness of colour names came with Michael Wilcox's book analysing watercolour paints The Wilcox Guide to the Finest Watercolours. This was the first time I realised that
  • every pigment has an international classification and standardised name
  • not every colour is what it says it is. In other words the names can continue even if the manufacturers has switched to using different pigments.
  • some of the labelling of watercolour paint has been misleading (an understatement!)
  • some manufacturers refuse to disclose which pigments are in their art media.
Paint labeling is probably the least interesting topic on watercolor paints ... like reading the fire tag on a new mattress. Unfortunately, boredom leads to apathy, and apathy leads to ignorance, and it is this ignorance that paint manufacturers exploit through marketing hype.

Paint labels tell you what your are getting for your money, provided you know the difference between pigments, paints and "colors". If you don't, then marketing gimmicks will take control.
First principles for art media communication

I've often heard it said that commercial considerations protect the secrets of how art media is made. I absolutely disagree and suggest this is a fallacy - which is essentially part of marketing hype.

I'd like to highlight a different perspective - one which is very much consumer oriented and very much connected to the whole process of classifying and naming - and selling - pigments, colours and paints.

I believe that
  • artists want to know what they are buying
  • consumers can set the standards for disclosure through the way they buy their art media
  • the following are the principles which a world-class art media manufacturer/distributor SHOULD always observe
I'm passionate about product delivery being consumer oriented and this is my manifesto!

All world class manufacturers, distributors and suppliers of art media ("the suppliers") have a duty to support an artist who wants to use good quality materials which are sourced in an ethical way.

World class art media suppliers recognise that supporting an artist is best achieved through the provision of all relevant information in an accessible format.

World class art media suppliers will always disclose:
  • all information relevant to the QUALITY OF THE PRODUCT and
    • lightfastness - the creation of art which will last
    • utility - the behaviour of pigments in a particular art medium
    • toxicity - the safety of an artist
  • all information relevant to an OBJECTIVE ANALYSIS OF QUALITY through
    • standardisation - relevant pigment information as per the international classification for naming pigments and paints
    • clarity - all relevant chemical information
    • toxicity - relevant safety information
    • good communication - the use of labels which conform to international quality standards
  • all information about sourcing which is relevant to ethical considerations
In my view, world class art media suppliers support the notion that colours sold in any art medium should be lightfast, serviceable, not endanger the artist, be described in such a way that the informed artist understands what they are buying and, finally, sourced in ways which are responsible and humane.

Why do I think a consumer-driven approach works?

Well, in my opinion, you only have to look at how the views of society and consumers drive other decisions to change ways in which products are manufactured and distributed - from everything associated with products which have an impact on global warming to the production of battery chickens.

The art world and art materials is essentially no different. Consumers are concerned about quality, safety, reliability and production processes which they think are acceptable.

I very much advocate speaking up and asking for the same information as industry gets (see below).

Standardisation of pigments and paints - international classification

Of course, the reality is that art media form a very small part of the overall market for pigment.

The major industrial uses of pigment and colour - which go way beyond the production of paint - have created the need for standardised quality control. (In other words - the consumers of pigments said they wanted to know what they're buying - see above!).

As a result, there are now international standards and international classification systems and international names for all pigments.

This classification and naming extends to analysis of what a colourant (pigment or dye) is and how it performs - and related to that are a range of other standards about how pigments and dyes should be tested in relation to their constituents and performance.

The International Organization for Standardization (ISO) has developed technical standards for the manufacture of pigments and dyes. ISO standards define various industrial and chemical properties, and how to test for them. The principal ISO standards that relate to all pigments are as follows: ASTM International (ASTM), originally known as the American Society for Testing and Materials, is an international standards organization that develops and publishes voluntary consensus technical standards for a wide range of materials, products, systems, and services. It has a Subcommittee on Artists' Paints and Related Materials - ASTM D01.57. It helps artists and consumers recognize product quality and safety when manufacturers' products conform to its Standards.

These are the sort of standards which - if suppliers comply and communicate that compliance - tell consumers an awful lot about whether or not a supplier meets world class standards.
Members of the Subcommittee include artists, educators, conservators, medical doctors, chemists and other materials scientists, and representatives from art materials manufacturers, artists' groups, manufacturers of testing equipment, and regulatory agencies...........ASTM D01.57.has developed and published eleven standards covering such topics as testing of pigments for lightfastness, labeling content, paint performance criteria, and the health hazard labelling of art materials. Three additional standards are currently in development.

ASTM D01.57's mission includes the education of artists through the dissemination of information about the Standards.
ASTM D01.57
So as you can see my "manifesto" is pretty close to what already exists.

From my perspective - the major problem is about gaining manufacturers' compliance with those standards and the communication of information about art media.

For example, one main area of weakness continues to be getting manufacturers to agree and use the same method for classifying lightfastness. One can only speculate as to the reasons why they decline to do so.....

Which is where the artist's voice comes in - it's up to you and me to ask suppliers to comply with recognised standards. It's essentially a question of mutual interest.

What's in a name? The standardisation of pigments and paints names

So - after the need for standards has been recognised and all the testing has been done - FINALLY we get to the standardisation of names.

Many of the names that we use for a lot of colours relate to their historical names. This may now bear absolutely no relation to their actual chemical constituents as substitutions have occurred over the years. Which means that historical pigment and dye names are no longer adequate for providing consumers with adequate information.
The commercial name under which a colorant is marketed does not necessarily give a precise indication of its hue. This is well illustrated by the wide divergence that frequently occurs between the commercial names used by different manufacturers for the same colorant.
color Index International - hue charts
Colour Index International is a reference database of manufactured color products and is used by manufacturers and consumers, such as artists. Colorants (both dyes and pigments) are listed according to Colour Index Generic Names and Colour Index Constitution Numbers.

The Colour Index was first printed in 1925 but is now published exclusively on the web and is jointly maintained by the Society of Dyers and Colourists and the American Association of Textile Chemists and Colorists. It's been adopted by many manufacturers of paints, inks, textiles, plastics, and colors - but NOT all manufacturers of art media

The purpose of the colour index is to have a method for defining colour accurately and objectively. The 4th edition of the Colour Index is now available

In the CII schema, each pigment has a generic index number that identifies it chemically, regardless of proprietary and historic names. The colour index generic name is defined as follows
Color Index Name: A classification name and serial number which when allocated to a commercial product allows the colorant part of that product to be uniquely identified within any Colour Index application class. This enables the particular commercial product to be classified along with other products whose essential colorant is of the same chemical constitution and in which the essential colorant results from a single chemical reaction or series of reactions.
CII - Color Index Name
The CI names for pigments generally start P (for pigment), then have a letter or letters to denote the colour group (eg R = Red) and then a number to indicate the precise chemical composition. This means it becomes a lot easier to tell whether pigment names reflect what the colour is called and whether or not lightfast pigments and dyes are being used.

PW - White pigments PW6 - Titanium white
PY - Yellow pigments PY35 - Cadmium yellow
PO - Orange pigments PO34 - Azo orange
PR - Red pigments PR112 - Naphthol red
PV - Violet pigments PV19 - Quinacridone rose
PB - Blue pigments PB29 - Ultramarine
PG - Green pigments PG7 - Phthalo green
PBr - Brown pigments PBr7 - Natural umber
PBk - Black pigments PBk11 - Oxide black

The CI Constitution number is "an index classification of a colorant or intermediate according to its chemical constitution". Both the name and constitution number represent the chemical composition of the pigments and dyes used in the colouring agent.

The chart at the top is the CII hue chart which is used as part of the color indexing process and is part of the record accessed via the online database. Unfortunately the rest of the database is subscription only - and I understand it's not cheap! I don't quite see how it's ever going to educate the public if it gaurds information in this way. They need to work out a price for a one day access only or view up to x records.

These authors and art suppliers provide listings about pigments and dyes and chemicals and color names
There are others as well - and there are others who provide absolutely no information whatsoever.

In other words it's a complete fallacy that pigment and colour names cannot be supplied. Those suppliers who don't supply them choose not supply artists with relevant information.

I'm thinking about having a post in the future which highlights all those companies which look like they might be seeking to achieve world class status as suppliers of art media - through the provision of excellent information about the quality of their art media!

Tomorrow - what needs to be communicated about pigments and dyes via label, website or brochure.

In the meantime - why don't you check your paints, pencils and pastels - and see if you can tell what pigment or dye has been used and what its chemical composition is................


The Making A Mark Project on Colour - previous posts

Resources for Artists information sites created by makingamark


  1. You've nailed one of my passions in this post. Since a manufacturer's behavior is determined by consumer's response to the product, perhaps many artists need to reconsider their own attitudes about their works. I've heard more times than I want to believe artists commenting that their art work's longevity doesn't concern them.

    Others remain completely unaware of the issues of lightfastness or safety; rather, they will buy any tube of paint that's bright and exciting. A big gap exists within how we educate budding artists about their materials, but a more serious matter is their attitudes toward what they do. Thanks for this fine work you're doing with color information.

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